Accurately measuring current draw

[Andrey Dmitriev]

We tried clamp meeters, they didn't seem to be accurate.
Proper power strip (with amp readings) should do the job.

-a 

-----Original Message-----
From: Eoin_Mcguinn at dell.com [mailto:Eoin_Mcguinn at dell.com] 
Sent: Wednesday, March 05, 2008 12:33 PM
To: asterisk at raouf.net; linux-poweredge at lists.us.dell.com
Subject: RE: Accurately measuring current draw

My understanding is that with clamp-meters, you have to have access to 
the live feed, physically separated from the neutral. 
If you have this, go ahead and try with a meter, but you are going to 
loose the Power Factor calculation which an in-line meter can provide.

The rule of thumb with supplies is that the loading should be designed 
around 75% of the available load. For example, 6 amps of an 8 amp 
supply.

Anyhow, my preference would be to obtain a power logger with a serial 
port output which will enable you to measure the consumption over a 
reasonable range.

-----Original Message-----
From: linux-poweredge-bounces at dell.com 
[mailto:linux-poweredge-bounces at dell.com] On Behalf Of Faris Raouf
Sent: 05 March 2008 13:30
To: linux-poweredge-Lists
Subject: Accurately measuring current draw

Following on from the discussions on the Kill-A-Watt in another thread, 
has anyone used a proper clamp meter for measuring current?

I'm thinking about buying a cheap-ish one ($80/£40), along with a 
plug-in device similar to the Kill-A-Watt in order to compare these two 
options (which I consider "slightly-pro" and "consumer" - the clamp 
meter is only slightly-pro because it isn't an expensive one - no 
calibration certificate etc.

But I'd appreciate any feedback on how accurate the Kill-A-Watt type 
products might be before I bother doing so.

What I mean by accurate in this sense is given, say, an 8A power feed in 
a data centre, I want to be 100% sure that if my test figures say each 
server takes less than 1A under extreme load and I have no more than 8 
of them I'm not going to trip the breaker.

If there's more to this than meets the eye (e.g. all that RMS stuff and 
god knows what else that I've forgotten about since I did my Physics) 
please can someone pipe up and let me know?


Faris.





_______________________________________________
Linux-PowerEdge mailing list
Linux-PowerEdge at dell.com
http://lists.us.dell.com/mailman/listinfo/linux-poweredge
Please read the FAQ at http://lists.us.dell.com/faq

_______________________________________________
Linux-PowerEdge mailing list
Linux-PowerEdge at dell.com
http://lists.us.dell.com/mailman/listinfo/linux-poweredge
Please read the FAQ at http://lists.us.dell.com/faq